Case assembly for a gas turbine engine

ABSTRACT

A case for a gas turbine engine includes an integrated HPC Diffuser case operable to contain a combustor section and a portion of a High Pressure Compressor.

Applicant hereby claims priority to U.S. Patent Application No. 61/707,570 filed Sep. 28, 2012, the disclosure of which is herein incorporated by reference.

BACKGROUND

The present disclosure relates to a gas turbine engine and, more particularly, to a case structure therefor.

Gas turbine engines, such as those that power modern commercial and military aircraft, generally include a compressor section to pressurize an airflow, a combustor section for burning a hydrocarbon fuel in the presence of the pressurized air, and a turbine section to extract energy from the resultant combustion gases. An engine case structure formed of multiple cases or modules to facilitate assembly surround these sections. Each cases typically abuts another case at a flange. The engine cases are subject to a harsh environment as the products of combustion at high temperature pass therethrough.

SUMMARY

A case for a gas turbine engine according to one disclosed non-limiting embodiment of the present disclosure includes an integrated High Pressure Compressor Diffuser case operable to contain a combustor section and a portion of a compressor section.

In a further embodiment of the foregoing embodiment, the integrated HPC Diffuser case is a housing with a reinforced area. In the alternative or additionally thereto, in the foregoing embodiment the reinforced area defines an increased thickness.

In a further embodiment of any of the foregoing embodiments, the integrated HPC Diffuser case includes a HPC flange to provide a bolted connection with a HPC case.

In a further embodiment of any of the foregoing embodiments, the integrated HPC Diffuser case includes a HPT flange to provide a bolted connection with a HPT case.

In a further embodiment of any of the foregoing embodiments, the integrated HPC Diffuser case includes a HPC flange to provide a bolted connection with a HPC case and a HPT flange to provide a bolted connection with a HPT case. In the alternative or additionally thereto, in the foregoing embodiment no flange is located between said HPC flange and said HPT flange. In the alternative or additionally thereto, in the foregoing embodiment a boss arrangement is located between said HPC flange and said HPT flange.

In a further embodiment of any of the foregoing embodiments, the portion of said compressor section includes two stages.

In a further embodiment of any of the foregoing embodiments, the portion of said compressor section includes two stages of an eight stage High Pressure Compressor.

A case assembly of a gas turbine engine according to another disclosed non-limiting embodiment of the present disclosure includes a fan case, an intermediate case boltable to said fan case, a High Pressure Compressor case boltable to said intermediate case, an integrated High Pressure Compressor Diffuser case boltable to said High Pressure Compressor case, a High Pressure Turbine case boltable to said integrated High Pressure Compressor Diffuser case, a Mid Turbine Frame case boltable to said High Pressure Turbine case, a Low Pressure Turbine case boltable to said Mid Turbine Frame case and a Turbine Exhaust case boltable to said Low Pressure Turbine case.

In a further embodiment of the foregoing embodiment, the integrated HPC Diffuser case includes a housing with a reinforced area. In the alternative or additionally thereto, in the foregoing embodiment the reinforced area defines an increased thickness.

In a further embodiment of any of the foregoing embodiments, the integrated HPC Diffuser case includes a HPC flange to provide a bolted connection with a HPC case and a HPT flange to provide a bolted connection with a HPT case. In the alternative or additionally thereto, in the foregoing embodiment a boss arrangement is located between said HPC flange and said HPT flange.

In a further embodiment of any of the foregoing embodiments, the integrated HPC Diffuser case is operable to contain a combustor section and a portion of a High Pressure Compressor.

In the alternative or additionally thereto, in the foregoing embodiment the portion of said High Pressure Compressor includes two stages. In the alternative or additionally thereto, in the foregoing embodiment the portion of said High Pressure Compressor includes two stages of an eight stage High Pressure Compressor.

In a further embodiment of any of the foregoing embodiments, the High Pressure Compressor case is a split case.

BRIEF DESCRIPTION OF THE DRAWINGS

Various features will become apparent to those skilled in the art from the following detailed description of the disclosed non-limiting embodiment. The drawings that accompany the detailed description can be briefly described as follows:

FIG. 1 is a schematic cross-section of a gas turbine engine;

FIG. 2 is a schematic view of a gas turbine engine case structure;

FIG. 3 is an expanded perspective view of an integrated HPC Diffuser case;

FIG. 4 is an expanded perspective view of a RELATED ART HPC rear case bolted to a Diffuser case; and

FIG. 5 is an expanded unrolled view of the integrated HPC Diffuser case illustrating a boss arrangement.

DETAILED DESCRIPTION

FIG. 1 schematically illustrates a gas turbine engine 20. The gas turbine engine 20 is disclosed herein as a two-spool turbo fan that generally incorporates a fan section 22, a compressor section 24, a combustor section 26 and a turbine section 28. Alternative engines might include an augmentor section (not shown) among other systems or features. The fan section 22 drives air along a bypass flowpath while the compressor section 24 drives air along a core flowpath for compression and communication into the combustor section 26 then expansion through the turbine section 28. Although depicted as a turbofan in the disclosed non-limiting embodiment, it should be understood that the concepts described herein are not limited to use with turbofans as the teachings may be applied to other types of turbine engines such as a turbojets, turboshafts, and three-spool (plus fan) turbofans wherein an intermediate spool includes an intermediate pressure compressor (“IPC”) between a Low Pressure Compressor (“LPC”) and a High Pressure Compressor (“HPC”), and an intermediate pressure turbine (“IPT”) between the high pressure turbine (“HPT”) and the Low pressure Turbine (“LPT”).

The engine 20 generally includes a low spool 30 and a high spool 32 mounted for rotation about an engine central longitudinal axis A relative to an engine case assembly 36 via several bearing structures 38. The low spool 30 generally includes an inner shaft 40 that interconnects a fan 42, a low pressure compressor 44 (“LPC”) and a low pressure turbine 46 (“LPT”). The inner shaft 40 drives the fan 42 directly or through a geared architecture 48 to drive the fan 42 at a lower speed than the low spool 30. An exemplary reduction transmission is an epicyclic transmission, namely a planetary or star gear system.

The high spool 32 includes an outer shaft 50 that interconnects a high pressure compressor 52 (“HPC”) and high pressure turbine 54 (“HPT”). A combustor 56 is arranged between the high pressure compressor 52 and the high pressure turbine 54. The inner shaft 40 and the outer shaft 50 are concentric and rotate about the engine central longitudinal axis A which is collinear with their longitudinal axes.

Core airflow is compressed by the LPC 44 then the HPC 52, mixed with the fuel and burned in the combustor 56, then expanded over the HPT 54 and the LPT 46. The turbines 54, 46 rotationally drive the respective low spool 30 and high spool 32 in response to the expansion. The main engine shafts 40, 50 are supported at a plurality of points by bearing structures 38 within the case assembly 36. It should be understood that various bearing structures 38 at various locations may alternatively or additionally be provided.

In one non-limiting example, the gas turbine engine 20 is a high-bypass geared aircraft engine. In a further example, the gas turbine engine 20 bypass ratio is greater than about six (6:1). The geared architecture 48 can include an epicyclic gear train, such as a planetary gear system or other gear system. The example epicyclic gear train has a gear reduction ratio of greater than about 2.3, and in another example is greater than about 2.5:1. The geared turbofan enables operation of the low spool 30 at higher speeds which can increase the operational efficiency of the low pressure compressor 44 and low pressure turbine 46 and render increased pressure in a fewer number of stages.

A pressure ratio associated with the low pressure turbine 46 is pressure measured prior to the inlet of the low pressure turbine 46 as related to the pressure at the outlet of the low pressure turbine 46 prior to an exhaust nozzle of the gas turbine engine 20. In one non-limiting embodiment, the bypass ratio of the gas turbine engine 20 is greater than about ten (10:1), the fan diameter is significantly larger than that of the low pressure compressor 44, and the low pressure turbine 46 has a pressure ratio that is greater than about five (5:1). It should be understood, however, that the above parameters are only exemplary of one embodiment of a geared architecture engine and that the present disclosure is applicable to other gas turbine engines including direct drive turbofans.

In one embodiment, a significant amount of thrust is provided by the bypass flow path B due to the high bypass ratio. The fan section 22 of the gas turbine engine 20 is designed for a particular flight condition—typically cruise at about 0.8 Mach and about 35,000 feet. This flight condition, with the gas turbine engine 20 at its best fuel consumption, is also known as bucket cruise Thrust Specific Fuel Consumption (TSFC). TSFC is an industry standard parameter of fuel consumption per unit of thrust.

Fan Pressure Ratio is the pressure ratio across a blade of the fan section 22 without the use of a Fan Exit Guide Vane system. The low Fan Pressure Ratio according to one non-limiting embodiment of the example gas turbine engine 20 is less than 1.45. Low Corrected Fan Tip Speed is the actual fan tip speed divided by an industry standard temperature correction of (“T”/518.7^(0.5)) in which “T” represents the ambient temperature in degrees Rankine. The Low Corrected Fan Tip Speed according to one non-limiting embodiment of the example gas turbine engine 20 is less than about 1150 fps (351 m/s).

With reference to FIG. 2, the engine case assembly 36 generally includes a multiple of cases or modules to include a fan case 60, an intermediate case 62, a HPC split case 64, an integrated High Pressure Compressor (HPC) diffuser case 66, a High Pressure Turbine (HPT) case 68, a mid turbine frame (MTF) case 70, a Low Pressure Turbine (LPT) case 72, and a Turbine Exhaust case (TEC) 74. The fan case 60 is bolted to the intermediate case 62 which is bolted to the HPC split case 64 which is bolted to the integrated HPC diffuser case 66 which is bolted to the HPT case 68 which is bolted to the mid turbine frame (MTF) case 70 which is bolted to the LPT case 72 which is bolted to the turbine exhaust case (TEC) 74 each at a respective flange. It should be understood that the order of assembly may not necessarily follow the disclosed description. That is, the cases 60-74 may be assembled or disassembled for maintenance at any interface.

In one disclosed non-limiting embodiment, the integrated HPC diffuser case 66 is mounted between the split HPC case 64 and the HPT case 68 to surround the last two stages of an eight (8) stage HPC 52 and the combustor 56. That is, the integrated HPC diffuser case 66 contains the combustor 56 and a portion of the HPC 52.

With reference to FIG. 3, the integrated HPC diffuser case 66 generally includes a housing 76 with a reinforced area 78. The reinforced area 78 is a selectively thickened area that provides strength in desired locations as compared with the separate structural arrangement provided by the heretofore utilized separate HPC rear case H and diffuser case D with a flange F therebetween (FIG. 4; RELATED ART).

The integrated HPC diffuser case 66 includes a HPC flange 80 to provide a bolted connection with the HPC split case 64 and a HPT flange 82 to provide a bolted connection with the HPT case 68. The integrated HPC diffuser case 66 provides a shorter overall engine length through elimination of the flange F (FIG. 4; RELATED ART) which facilitates a more efficient and compact boss arrangement 84 (FIG. 5).

With reference to FIG. 5, a row fuel injector bosses 86 are arranged generally along the middle of the integrated HPC diffuser case 66 between the flanges 80, 82. Environmental Control System (ECS) bosses 88 are telescoped at least partially into the row fuel injector bosses 86. It should be appreciated that various bosses may additionally or alternatively be provided.

It should be understood that relative positional terms such as “forward,” “aft,” “upper,” “lower,” “above,” “below,” and the like are with reference to the normal operational attitude of the vehicle and should not be considered otherwise limiting.

It should be understood that like reference numerals identify corresponding or similar elements throughout the several drawings. It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom.

Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present disclosure.

The foregoing description is exemplary rather than defined by the limitations within. Various non-limiting embodiments are disclosed herein, however, one of ordinary skill in the art would recognize that various modifications and variations in light of the above teachings will fall within the scope of the appended claims. It is therefore to be understood that within the scope of the appended claims, the disclosure may be practiced other than as specifically described. For that reason the appended claims should be studied to determine true scope and content. 

What is claimed is:
 1. A case for a gas turbine engine comprising: an integrated High Pressure Compressor Diffuser case operable to contain a combustor section and a portion of a compressor section.
 2. The case as recited in claim 1, wherein said integrated HPC Diffuser case is a housing with a reinforced area.
 3. The case as recited in claim 2, wherein said reinforced area defines an increased thickness.
 4. The case as recited in claim 1, wherein said integrated HPC Diffuser case includes a HPC flange to provide a bolted connection with a HPC case.
 5. The case as recited in claim 1, wherein said integrated HPC Diffuser case includes a HPT flange to provide a bolted connection with a HPT case.
 6. The case as recited in claim 1, wherein said integrated HPC Diffuser case includes a HPC flange to provide a bolted connection with a HPC case and a HPT flange to provide a bolted connection with a HPT case.
 7. The case as recited in claim 6, wherein no flange is located between said HPC flange and said HPT flange.
 8. The case as recited in claim 7, wherein a boss arrangement is located between said HPC flange and said HPT flange.
 9. The case as recited in claim 1, wherein said portion of said compressor section includes two stages.
 10. The case as recited in claim 1, wherein said portion of said compressor section includes two stages of an eight stage High Pressure Compressor.
 11. A case assembly of a gas turbine engine comprising: a fan case; an intermediate case boltable to said fan case; a High Pressure Compressor case boltable to said intermediate case; an integrated High Pressure Compressor Diffuser case boltable to said High Pressure Compressor case; a High Pressure Turbine case boltable to said integrated High Pressure Compressor Diffuser case; a Mid Turbine Frame case boltable to said High Pressure Turbine case; a Low Pressure Turbine case boltable to said Mid Turbine Frame case; and a Turbine Exhaust case boltable to said Low Pressure Turbine case.
 12. The case assembly as recited in claim 11, wherein said integrated HPC Diffuser case includes a housing with a reinforced area.
 13. The case assembly as recited in claim 12, wherein said reinforced area defines an increased thickness.
 14. The case assembly as recited in claim 13, wherein said integrated HPC Diffuser case includes a HPC flange to provide a bolted connection with a HPC case and a HPT flange to provide a bolted connection with a HPT case.
 15. The case assembly as recited in claim 14, wherein a boss arrangement is located between said HPC flange and said HPT flange.
 16. The case assembly as recited in claim 11, wherein said integrated HPC Diffuser case is operable to contain a combustor section and a portion of a High Pressure Compressor.
 17. The case assembly as recited in claim 16, wherein said portion of said High Pressure Compressor includes two stages.
 18. The case assembly as recited in claim 16, wherein said portion of said High Pressure Compressor includes two stages of an eight stage High Pressure Compressor.
 19. The case assembly as recited in claim 11, wherein said High Pressure Compressor case is a split case. 